Light beams define new 3D printing ink


A team of Australian researchers has developed an ink that could be used in an entirely new concept of potentially much faster 3D printing.

In this technology, a beam of light from a laser passes through the ink, exciting the atoms in its path. Some of the molecules change shape when hit by light, but they don’t react with anything – yet. A second beam of light, of a different color, hits the ink from a different angle, causing contortions in a different set of molecules.

At the intersection of these light beams, the two excited molecules react with each other and become solid.

This is the idea that drives the new 3D printing technique.

“Normally, in a 3D printer, the inkjet travels in two dimensions, slowly printing a 2D layer before rising to print another layer on top,” says Materials Science Center researcher Dr. Sarah Walden from Queensland University of Technology.

“But using this technology, you can activate an entire two-dimensional sheet and print the entire sheet at once.”

This technology is about to hit the market, but there are a few things holding it back.

“These two-color printers are under development. There is a commercial one on the market,” says Walden.

Currently, it is difficult to find substances that react to specific shades of light – and react with each other. This is where the research of Walden and his colleagues comes in.

“We’re making inks that could be used in this kind of printing, and we think that could really speed up the speed at which we 3D print materials,” says Walden.

The team comes from published a paper in Nature Communication describing one of these inks.

“We tried a lot of things that didn’t work, like you do in research. It was great to finally find a system that behaves well,” says Walden.

The system works by manipulating two substances: one a type of chemical called azobenzene and the other a type of ketene. These two chemicals do not react with each other under typical conditions. But when the molecules are exposed to light (red or green light in the case of azobenzene, UV light in the case of ketene), each changes shape to one that causes them to react with each other to form a solid compound.

This trick means that in the absence of both shades of light, nothing happens to the substance, which means it can be used in further crafting processes.

“We use the colors of light to essentially transform them into their reactive forms,” Walden summarizes.

“But if they don’t find a reactive partner, they just go back to their non-reactive forms. So when we turn off the light, there will be no reaction afterwards. »

Read more: Shedding light on the manufacture of molecules

The researchers first tested the process with a tunable laser at QUT labs, but were later able to replicate it with commercially available light-emitting diodes (LEDs).

Walden says that, so far, the technology has been used to make proof-of-concept wearables.

“We’ve made few materials in our lab, so we know this two-color process works,” she says.

The interdisciplinary team wants to find other chemicals that can react to light and each other like that.

“You can start thinking about materials that are kind of biocompatible with visible light – but that’s well on the way,” says Walden.


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